Method for the production of polymer surface metallization coatings based on cold gas dynamic spraying and friction stir processing

Abstract

The present application belongs to the technical field of polymer surface metallization, and particularly relates to a preparation method of polymer surface metallization coating based on cold gas dynamic spraying and friction stir processing. The method comprises the following steps: (1) using a cold gas dynamic spraying device, spraying metal powder (such as Al, Cu, Ti, Ag, Sn, etc.) to the surface of a polymer substrate (such as PEEK, PEI, PA6, ABS and their composite materials, etc.) under certain conditions to form a cold sprayed metal coating; (2) using a friction stir welding center to perform friction stir processing on the deposited cold sprayed coating and the interface between the coating and the polymer substrate, so as to obtain a high-conductivity and high-bonding-strength metallized coating on the surface of the polymer substrate. The method combines the advantages of cold gas dynamic spraying technology and friction stir processing technology, and opens up a new process route for polymer and polymer-based composite material surface metallization.

Description

Technical Field

[0001] This invention belongs to the field of polymer surface metallization technology, specifically relating to a method for preparing a polymer surface metallization coating based on cold gas dynamic spraying and friction stirring treatment. Background Technology

[0002] With the increasing demand for lightweight structural materials across various fields, polymers and polymer-based composites have been widely applied. However, due to their poor electrical and thermal conductivity, lightweight polymers have brought many new problems when replacing metallic structural materials. For example, aircraft made of polymer-based composites are easily damaged by lightning strikes because the current cannot be transmitted in time; radar antennas made of polymers cannot provide electromagnetic shielding. Preparing metallized functional coatings on the surface of polymer materials can endow them with electrical and thermal conductivity, meeting the needs of certain applications in industry and defense that require both lightweight and conductive / thermal conductive components. Cold aerodynamic spraying technology is an aerodynamic coating preparation technique. Powder particles are accelerated to 300–1500 m / s through a delaval tube, collide with the substrate, deform, and bond, thus forming a coating. Compared to thermal spraying technology, it can prepare low-oxidation, low-stress pure metallic coatings at relatively lower temperatures. Furthermore, its "cold" characteristic is beneficial for preparing metallized coatings on temperature-sensitive materials.

[0003] However, due to their low heat distortion temperature, polymer materials cannot withstand excessively high energy input. Using high parameters (accelerator gas temperature, pressure) during cold gas spraying can cause deformation of the polymer matrix and even damage to its molecular structure. Conversely, using low parameters or low-pressure cold spraying equipment results in poor bonding between deformed particles within the metal coating, leading to low electrical conductivity. Furthermore, the poor physical properties of the metal and polymer result in weak adhesion between the coating and the substrate. Since the working temperature of the polymer material cannot reach the heat treatment temperature of the metal coating, commonly used post-cold spraying heat treatment methods are also unusable. Therefore, there is an urgent need to develop a post-cold spraying treatment method to improve the performance (electrical conductivity, adhesion strength) of cold-sprayed polymer coatings. Friction stirring post-treatment utilizes the high-speed rotation of the stirring head to force material flow, thereby improving the bonding of deformed particles within the cold-sprayed coating and increasing the coating's electrical conductivity. Simultaneously, it can form a macroscopic polymer-metal mixing zone at the coating / substrate interface, enhancing the coating's adhesion strength. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stir treatment. The method adopts a process route that combines cold gas dynamic spraying and friction stir treatment to prepare a metallized coating (such as Al, Cu, Ti, Ag, Sn, etc.) with high electrical conductivity and high bonding strength on the surface of polymers such as PEEK, PEI, PA6, ABS and their composite materials.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stir treatment is disclosed. The method adopts a process route that combines cold gas dynamic spraying and friction stir treatment to prepare a metallized coating with high conductivity and high bonding strength on the surface of a polymer matrix.

[0007] The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment, wherein the polymer matrix is ​​one of PEEK and PEEK-based composite materials, PEI and PEI-based composite materials, PA6 and PA6-based composite materials, ABS and ABS-based composite materials; and the metallized coating component is one of Al, Cu, Ti, Ag, and Sn.

[0008] The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment has a metallized coating thickness of 300–3000 μm.

[0009] The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring includes the following steps:

[0010] (1) A cold-spray metal coating is formed by spraying metal powder onto the surface of a polymer matrix using a cold-powder power spraying equipment.

[0011] (2) A friction stir welding center is used to perform friction stir treatment on the cold sprayed metal coating and its interface with the polymer matrix to improve the electrical conductivity and bonding strength of the coating.

[0012] In the method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment, in step (1), the metal powder used for spraying has a spherical or irregular morphology, a particle size range of 5-70 μm, and a powder purity >95 wt%.

[0013] In the method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment, in step (1), the polymer substrate needs to be cleaned with acetone, anhydrous ethanol and deionized water in sequence before spraying to ensure the cleanliness of the substrate surface.

[0014] In the method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment, in step (1), the cold gas dynamic spraying uses compressed air, nitrogen or helium as the propellant gas, the gas heating temperature is 180 to 600°C, the gas working pressure is 0.5 to 5.0 MPa, and the spraying distance is 10 to 40 mm.

[0015] The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment selects the optimal cold gas dynamic spraying parameters by analyzing the metallographic structure of the sprayed state.

[0016] In the method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment, in step (2), a tungsten carbide or tool steel stirring head is used during the friction stirring treatment. The diameter between the shafts is 10-30 mm, the needle length is 2-5 mm, the forward speed of the stirring head is 5-200 mm / min, the rotation speed is 300-2000 r / min, and the spindle tilt angle is 0-5°.

[0017] The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment selects the optimal friction stirring treatment parameters by analyzing the metallographic structure after friction stirring treatment.

[0018] The design concept of this invention is:

[0019] This invention utilizes cold gas dynamic spraying technology to prepare a low-oxidation, pure metallized coating on the surface of a polymer matrix without damaging it. Subsequently, a stir-friction treatment technique is employed to improve the bonding of deformable particles within the cold-sprayed coating, thereby increasing the coating's electrical conductivity. Simultaneously, a macroscopic polymer-metal hybrid zone is formed at the coating / matrix interface, enhancing the coating's bonding strength.

[0020] The beneficial effects of the technical solution of this invention are:

[0021] 1. The method of the present invention can prepare a metallized coating directly on the surface of a workpiece without damaging the polymer material by means of cold gas dynamic spraying process.

[0022] 2. The present invention uses friction stirring as a post-treatment method for spraying. On the one hand, it can improve the bonding of deformed particles inside the cold spray coating and increase the electrical conductivity of the coating. On the other hand, it can form a macroscopic polymer-metal mixed zone, which can improve the bonding strength of the coating and the shear strength can reach more than 35 MPa. Attached Figure Description

[0023] Figure 1 SEM images of cross sections after friction stir treatment of PEEK surface with Al coating applied by cold gas dynamic spraying: (a) SEM image of the inside of the coating; (b) SEM image of the interface mixing zone.

[0024] Figure 2 SEM image of the cross section of PA6 after cold gas dynamic spraying of an Al coating followed by friction stirring treatment. Detailed Implementation

[0025] In the specific implementation process, firstly, a cold-powder spraying device is used to spray metal powder onto the surface of the polymer substrate to form a sprayed coating. Secondly, a friction stir welding center is used to perform friction stir treatment on the deposited cold-sprayed coating to improve the conductivity and bonding strength of the cold-sprayed metallized coating. The specific steps of this method are as follows:

[0026] (1) Cleaning: The polymer is cleaned by using acetone, anhydrous ethanol and deionized water in sequence, through ultrasonic cleaning and dehydration processes.

[0027] (2) Preparation of cold spray coating: Using cold air power spraying equipment, metal powder (such as Al, Cu, Ti, Ag, Sn, etc.) is sprayed and deposited onto the surface of polymer matrix (such as PEEK, PEI, PA6, ABS and other polymers and their composites) under certain conditions.

[0028] (3) Friction stirring treatment: The deposited cold spray coating is subjected to friction stirring treatment using a friction stirring welding center to improve the performance of the sprayed coating.

[0029] The metal powder in step 2 has a spherical or irregular morphology, a particle size range of 5–70 μm (preferably 10–35 μm), and a purity greater than 95 wt%. Cold gas-powered spraying uses compressed air, nitrogen, or helium as the propellant gas, with a gas heating temperature of 180–600℃ (preferably 200–380℃), a gas working pressure of 0.5–5.0 MPa (preferably 0.5–3.0 MPa), and a spraying distance of 10–40 mm (preferably 10–20 mm). For cold gas-powered spraying equipment, please refer to the cold gas-powered spraying device mentioned in Chinese Invention Patent (Patent No.: 01128130.8, Authorization Announcement No.: CN1161188C) or other commercial cold gas-powered spraying, power spraying, or low-pressure cold gas-powered spraying equipment. The spray gun is a De-Laval spray gun made of carbon steel, tungsten carbide, or PBI material.

[0030] In step 3, a tungsten carbide or tool steel stirring head is used for the stirring friction treatment. The shaft diameter is 10-30 mm (preferably 10-20 mm), the needle length is 2-5 mm (preferably 2-3 mm), the stirring head advance speed is 5-200 mm / min (preferably 5-30 mm / min), the rotation speed is 300-2000 r / min (preferably 1000-1500 r / min), and the main shaft tilt angle is 0-5° (preferably 0°).

[0031] The embodiments of the present invention will be described in detail below. They are implemented based on the technical solutions of the invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] In this embodiment, the method for preparing an Al coating on a PEEK surface based on cold gas dynamic spraying and friction stir treatment includes the following steps:

[0034] (1) The PEEK substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water to remove surface oil.

[0035] (2) Atomized Al powder with a particle size of 30-40 μm is deposited on the surface of PEEK substrate by cold gas dynamic spraying. The purity of Al powder is ≥99.5 wt%. The accelerating gas for cold gas dynamic spraying is N2, the accelerating gas temperature is 380℃, the accelerating gas pressure is 3.0 MPa, and the spraying distance is 20 mm to form a pure Al coating with a thickness of ~2 mm.

[0036] (3) A friction stir welding center was used to perform friction stir treatment on the deposited cold spray coating to improve the performance of the sprayed coating. The stirring head was made of tool steel with a shaft diameter of 10 mm and a needle length of 2.2 mm. The stirring head forward speed was 20 mm / min, the rotation speed was 1500 r / min, the spindle tilt angle was 0°, and the Al coating thickness after friction stir treatment was ~1.8 mm.

[0037] like Figure 1 As shown in (a) and (b), the Al coating on the PEEK surface obtained in this embodiment is dense inside, with no obvious boundaries of cold-sprayed particles, as can be seen from the cross-sectional photographs after the Al coating has been treated with stirring and friction. Its conductivity is comparable to that of bulk Al. The Al coating and the PEEK substrate are in a mixing zone, and the shear strength can reach 50 MPa.

[0038] Example 2

[0039] In this embodiment, the method for preparing the Al coating on the PA6 surface based on cold gas dynamic spraying and friction stir treatment includes the following steps:

[0040] (1) The PA6 substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water to remove surface oil.

[0041] (2) Atomized Al powder with a particle size of 20-30 μm is deposited on the surface of PA6 substrate by cold gas dynamic spraying. The purity of Al powder is ≥99.9 wt%. The accelerating gas for cold gas dynamic spraying is N2, the accelerating gas temperature is 300℃, the accelerating gas pressure is 3.0 MPa, the spraying distance is 20 mm, and a metal Al coating with a thickness of ~2 mm is formed.

[0042] (3) A friction stir welding center was used to perform friction stir treatment on the deposited cold spray coating to improve the performance of the sprayed coating. The stirring head was made of tool steel with a shaft diameter of 10 mm and a needle length of 2.2 mm. The stirring head forward speed was 5 mm / min, the rotation speed was 1500 r / min, the spindle tilt angle was 0°, and the Al coating thickness after friction stir treatment was ~1.8 mm.

[0043] like Figure 2 As shown in the figure, the PA6 surface Al coating obtained in this embodiment, as can be seen from the cross-sectional photograph after the Al coating is treated by stirring and friction, has a dense interior with no obvious boundaries of cold-sprayed particles, its conductivity is comparable to that of bulk Al, and its shear strength can reach 55 MPa.

[0044] Example 3

[0045] In this embodiment, the method for preparing a Cu coating on an ABS surface based on cold gas dynamic spraying and friction stir treatment includes the following steps:

[0046] (1) The ABS substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water to remove surface oil.

[0047] (2) Atomized Cu powder with a particle size of 10-20 μm is deposited on the surface of ABS substrate by cold gas dynamic spraying. The purity of Cu powder is ≥99.9 wt%. The accelerating gas for cold gas dynamic spraying is helium, the accelerating gas temperature is 200℃, the accelerating gas pressure is 1.5 MPa, and the spraying distance is 10 mm to form a metal Cu coating with a thickness of ~1.5 mm.

[0048] (3) A friction stir welding center was used to perform friction stir treatment on the deposited cold spray coating to improve the performance of the sprayed coating. The stirring head was made of tool steel with a shaft diameter of 15 mm and a needle length of 2.0 mm. The stirring head forward speed was 30 mm / min, the rotation speed was 1200 r / min, the spindle tilt angle was 0°, and the thickness of the Cu coating after friction stir treatment was 1.3 mm.

[0049] The Cu coating on the ABS surface obtained in this embodiment is dense inside, with no obvious boundaries of cold-sprayed particles, and its conductivity is comparable to that of bulk Cu. The Cu coating and the ABS substrate are in a mixed zone, and the shear strength can reach 35 MPa.

[0050] Example 4

[0051] In this embodiment, the method for preparing a Ti coating on a PEI surface based on cold gas dynamic spraying and friction stir treatment includes the following steps:

[0052] (1) The PEI substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water to remove surface oil.

[0053] (2) Atomized Ti powder with a particle size of 50-60 μm is deposited on the surface of PEI substrate by cold gas dynamic spraying. The purity of Ti powder is ≥99.9 wt%. The accelerating gas for cold gas dynamic spraying is helium, the accelerating gas temperature is 200℃, the accelerating gas pressure is 2.0 MPa, and the spraying distance is 15 mm to form a metallic Ti coating with a thickness of ~1.5 mm.

[0054] (3) A friction stir welding center was used to perform friction stir treatment on the deposited cold spray coating to improve the performance of the sprayed coating. The stirring head was made of tool steel with a shaft diameter of 20 mm and a needle length of 2.6 mm. The stirring head forward speed was 25 mm / min, the rotation speed was 1000 r / min, the spindle tilt angle was 0°, and the thickness of the Ti coating after friction stir treatment was ~1.3 μm.

[0055] The Ti coating on the PEI surface obtained in this embodiment is dense inside, with no obvious boundaries of cold-sprayed particles, and its conductivity is comparable to that of bulk Ti. The Ti coating and the PEI substrate are in a mixed region, and the shear strength can reach 45 MPa.

[0056] The results of the examples demonstrate that this invention combines the advantages of cold gas dynamic spraying and friction stir treatment. It can obtain a highly conductive and highly bonded metallized coating on the polymer matrix surface, opening up a new process route for the metallization of polymer and polymer-based composite surfaces.

Claims

1. A method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stir treatment, characterized in that, A process combining cold gas dynamic spraying and friction stir treatment is used to prepare a highly conductive and high-bonding metallized coating on the surface of a polymer matrix, including the following steps: (1) A cold-spray metal coating is formed by spraying metal powder onto the surface of a polymer matrix using a cold-powder power spraying equipment; the polymer matrix is ​​one of PEEK and PEEK-based composite materials, PEI and PEI-based composite materials, PA6 and PA6-based composite materials, ABS and ABS-based composite materials; the cold-spray power spraying uses compressed air, nitrogen or helium as the propellant gas, the gas heating temperature is 180 to 600°C, the gas working pressure is 0.5 to 5.0 MPa, and the spraying distance is 10 to 40 mm; (2) A friction stir welding center is used to perform friction stir treatment on the cold spray metal coating and its interface with the polymer matrix to improve the electrical conductivity and bonding strength of the coating. When performing friction stir treatment, a tungsten carbide or tool steel stirring head is used with an inter-shaft diameter of 10-30 mm, a needle length of 2-5 mm, a stirring head forward speed of 5-200 mm / min, a rotation speed of 300-2000 r / min, and a spindle tilt angle of 0-5°. The friction stir treatment technology improves the bonding of deformable particles inside the cold spray coating, increases the electrical conductivity of the coating, and at the same time forms a macroscopic polymer-metal mixing zone at the coating / matrix interface to improve the bonding strength of the coating.

2. The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment according to claim 1, characterized in that, The metallization coating is composed of one of Al, Cu, Ti, Ag, and Sn.

3. The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment according to claim 1, characterized in that, The thickness of the metallized coating is 300–3000 μm.

4. The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment according to claim 1, characterized in that, In step (1), the metal powder used for spraying has a spherical or irregular shape, a particle size range of 5 to 70 μm, and a powder purity of >95 wt%.

5. The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment according to claim 1, characterized in that, In step (1), the polymer substrate needs to be cleaned with acetone, anhydrous ethanol and deionized water in sequence before spraying to ensure the cleanliness of the substrate surface.

6. The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment according to claim 1, characterized in that, The optimal cold gas dynamic spraying parameters were selected based on the metallographic structure of the sprayed state.

7. The method for preparing a polymer surface metallized coating based on cold gas dynamic spraying and friction stirring treatment according to claim 1, characterized in that, The optimal stirring and friction treatment parameters were selected based on the metallographic structure after stirring and friction treatment.

Images